Radiator warranty

I had the boiler and 7 radiators replaced 4 years ago when I moved into my house. I was happy with the work and have had the company back every year for boiler service.

A couple of weeks ago I found leaks coming from two of the radiators. I booked the people to come out to do boiler service (it was due) and whilst he was here I asked him for his advice regarding the leaking radiators. He said it's a leak from the actual radiator itself as opposed to a valve or anything so the whole radiator needs replacing. He made some calls and said they have a 10 year warranty. But then followed that by saying that he hasn't kept his receipts and the radiator supplier has been bought out so I probably can't get them replaced under warranty after all, but to leave it with him.

I chased a few weeks later after not hearing anything and his response was to send me a quote for 2 new radiators plus labour fees.

I don't feel like it's right that I should have to pay to replace them if they're under warranty? Can anyone in the business please advise before I pay him any more money?